On Mon, Jan 24, 2011 at 9:57 PM, Ralf Baechle <ralf@xxxxxxxxxxxxxx> wrote:
> On Thu, Jan 20, 2011 at 03:28:29AM +0800, Wu Zhangjin wrote:
>
>> @@ -91,10 +91,16 @@ int ftrace_make_nop(struct module *mod,
>> unsigned long ip = rec->ip;
>>
>> /*
>> - * We have compiled module with -mlong-calls, but compiled the kernel
>> - * without it, we need to cope with them respectively.
>> + * If ip is in kernel space, no long call, otherwise, long call is
>> + * needed.
>> */
>
> Or even better, just check if the destination is in the same 28-bit segment
> of address space. Something like:
>
> if ((src ^ dst) >> 28) {
> /* out of range of simple R_MIPS_26 relocation */
> }
Yeah, will check if the following statement works:
if ((rec->ip ^ _mcount) >> 28) {
...
}
This check may be faster and clearer ;-)
>
> That way you no longer rely on a particular address layout - and there are
> plans to change the address space layout eventually!
Yeah, we really need an address space independent method.
Thanks & Regards,
Wu Zhangjin
>
> Ralf
>
